1. Field of the Invention
This invention relates generally to tools used to complete subterranean wells and more particularly relates to apparatus and methods for use in performing gravel pack operations.
2. Description of Related Art
Hydrocarbon fluids such as oil and natural gas are obtained from a subterranean geologic formation, referred to as a reservoir, by drilling a well that penetrates the hydrocarbon-bearing formation. Once a wellbore has been drilled, the well must be completed before hydrocarbons can be produced from the well. A completion involves the design, selection, and installation of equipment and materials in or around the wellbore for conveying, pumping, or controlling the production or injection of fluids. After the well has been completed, production of oil and gas can begin.
Sand or silt flowing into the wellbore from unconsolidated formations can lead to an accumulation of fill within the wellbore, reduced production rates and damage to subsurface production equipment. Migrating sand has the possibility of packing off around the subsurface production equipment, or may enter the production tubing and become carried into the production equipment. Due to its highly abrasive nature, sand contained within production streams can result in the erosion of tubing, flowlines, valves and processing equipment. The problems caused by sand production can significantly increase operational and maintenance expenses and can lead to a total loss of the well.
One means of controlling sand production is the placement of relatively large sand (i.e., xe2x80x9cgravelxe2x80x9d) around the exterior of a slotted, perforated, or other type liner or screen. The gravel serves as a filter to help assure that formation fines and sand do not migrate with the produced fluids into the wellbore. In a typical gravel pack completion, a screen is placed in the wellbore and positioned within the unconsolidated formation that is to be completed for production. The screen is typically connected to a tool that includes a production packer and a cross-over, and the tool is in turn connected to a work or production tubing string. The gravel is mixed with a carrier fluid and is pumped in a slurry down the tubing and through the cross-over, thereby flowing into the annulus between the screen and the wellbore. The carrier fluid in the slurry leaks off into the formation and/or through the screen. The screen is designed to prevent the gravel in the slurry from flowing through it and entering the production tubing. As a result, the gravel is deposited in the annulus around the screen where it becomes tightly packed, forming a xe2x80x9cgravel pack.xe2x80x9d It is important to size the gravel for proper containment of the formation sand, and the screen must be designed in a manner to prevent the flow of the gravel through the screen.
A problem that is frequently encountered in a gravel pack completion, especially in long or highly deviated sections, is the formation of gravel bridges in the annulus between the wellbore and the tubing string. Non-uniform gravel packing of the annulus between the screen and the wellbore often occurs as a result of the premature loss of carrier fluid from the slurry. The fluid can be lost into high permeability zones within the formation, leading to the creation of gravel bridges in the annulus before all the gravel has been placed. These gravel bridges can further restrict the flow of slurry through the annulus, which can result in voids within the gravel pack. Once the well is placed on production, the flow of produced fluids will tend to be concentrated through any voids in the gravel pack, which can result in the migration of fines and sand into the produced fluids and lead to the problems discussed above. Over time the gravel that is deposited within the annulus may have a tendency to settle and fill any void areas, thereby loosening the gravel pack that is located higher up in the wellbore, and potentially creating new voids in areas adjacent to producing formations.
To alleviate these problems, alternate path devices have been proposed that provide better distribution of the gravel throughout the completed interval. These systems typically provide an alternate path, such as through a conduit element, which extends along the length of the sand screens. If a bridge forms in the annulus area, the slurry can flow through the conduit element and into the annulus area below the bridge, thus enabling the filling of the annulus area below the bridge with gravel. To gravel pack a productive interval of substantial length, multiple sections of sand screens need to be is joined to provide the necessary length. The conduit elements also need to be joined to provide alternate path coverage over the entire productive interval. After the sand screen sections have been joined, jumper tubes can be used to connect the lengths of conduit that are located adjacent the sand screens. Having to make two separate connections, the sand screens and the conduits, is time consuming and results in increased rig time and cost.
There is a need for improved tools and methods to connect sand screens and their adjacent conduit elements.
One embodiment of the present invention is a tubular housing. The tubular housing comprises a housing wall defining a longitudinal bore providing a first fluid communication path therethrough. The housing wall further defining a longitudinal passageway providing a second fluid communication path therethrough. First and second ends provide for connecting a first sand screen assembly and a second sand screen assembly to the tubular housing.
The first fluid communication path is capable of communicating fluid flow from the first sand screen assembly to the second sand screen assembly. The second fluid communication path is capable of communicating fluid flow from a first alternate path element to a second alternate path. The longitudinal bore can be located eccentric with respect to the housing.
The tubular housing can comprise a first segment and a second segment releasably engaged. The first and second segments can be releasably engaged by threaded connectors, the threaded connectors capable of comprising timed threads capable of aligning the first and second segments. The first ends are capable of being attached to the sand screen assembly by welding. The first and second ends can be hingedly connected. The tubular housing can further comprise a sealing element that provides a seal for the first and second communication paths. Another embodiment of the invention is a wellbore completion system comprising a plurality of sand screen assemblies, the sand screen assemblies comprising screen members and alternate path members. The tool comprises least one connector having a wall defining an eccentric longitudinal bore, and a longitudinal passageway. The connector is provided for connecting the plurality of sand screen assemblies in fluid communication. The longitudinal bore of the at least one connector provides fluid communication between the screen members of the connected sand screen assemblies, and the longitudinal passageway provides fluid communication between the alternate path members of the connected sand screen assemblies. The at least one connector connects adjacent sand screen assemblies with the single make-up of the at least one connector.
Yet another embodiment is a connector comprising a tubular housing having a first end, a second end, an outer diameter and a housing wall, the outer diameter and housing wall defining an eccentric longitudinal bore. A longitudinal passageway defined by the housing wall provided for fluid communication between the first end and second end of the housing therethrough the housing wall. At least one of the first and second ends can comprise couplings. The couplings are provided for connecting two sand screen assemblies, the sand screen assemblies comprising screen elements and alternate path elements, the longitudinal bore providing fluid communication between the screen elements and the longitudinal passageway providing fluid communication between the alternate path elements. The couplings can comprise threaded elements or clamping elements and can be capable of being welded to the sand screen assemblies. The threaded elements can comprise timed threads capable of aligning the sand screen assemblies. The couplings can also comprise sealing elements.
The tubular housing can comprise a first section and one or more other sections, the first section comprising the longitudinal passageway. The sections can be joined by hinge elements and the connector is adapted for moving between an open position and a closed position. When the connector is in its closed position it is capable of connecting two sand screen assemblies and providing fluid communication between sand screen elements of the sand screen assemblies, and it is capable of providing fluid communication between alternate path elements of the sand screen assemblies. The longitudinal bore provides fluid communication between the sand screen elements of the two sand screen assemblies and the longitudinal passageway provides fluid communication between the alternate path elements of the two sand screen assemblies.
Still another embodiment is a connector comprising a first segment and a second segment, each segment comprising a first and second end. The first and second segments each comprise a housing wall defining a longitudinal bore providing a first fluid communication path therethrough, the housing wall further defining a longitudinal passageway providing a second fluid communication path therethrough. The first and second segments each comprise a first end having timed thread elements, the timed thread elements are capable of aligning the longitudinal bores and longitudinal passageways of the first and second segments while releasably connecting the first and second segments of the connector. The first and second segments can each comprise a second end capable of connecting to a sand screen assembly containing an alternate path element. The first and second segments can be capable of releasably connecting two sand screen assemblies and their alternate path elements.
An alternate embodiment of the invention is a wellbore completion method. The method comprising: providing a plurality of sand screen assemblies, the sand screen assemblies comprising screen members and alternate path members; providing at least one connector having a wall, the at least one connector comprising a longitudinal bore, and a longitudinal passageway within the connector wall; and connecting the plurality of sand screen assemblies with the make-up of the at least one connector, thereby providing fluid communication between the screen members of joined sand screen assemblies and between alternate path members of joined sand screen assemblies. The method can further comprise inserting the connected sand screen assemblies into the wellbore and performing a gravel pack completion on the wellbore. The alternate path members can be used as a conduit for hydraulic, pneumatic, electrical or fiber optic transmissions.